The private equity firm is paying a premium that amounts to 53%, according to data firm Dealogic, which based the figure on where ADT shares traded a week ago. That’s more than double the 26% premium for global M&A deals overall year-to-date, a stretch in which Dealogic calculates there have been 4,553 transactions worth a total of $378.7 billion.

There’s more to the numbers, however. Looking only at financial sponsor deals, such as those done by private equity firms like Apollo Global, the premium worldwide was substantially lower, just 17% year to date. So by that score it looks like ADT shareholders got a good deal.

The lower premiums typically paid by private equity firms may be due to the difficulty they face in finding cost savings compared to a strategic buyer, like a competitor, which can typically find myriad ways to streamline, consolidate, and otherwise prune costs.

Apollo Global, however, is folding ADT, a former unit of conglomerate Tyco International PLC, into Protection 1, a business and home security company the private equity firm bought last year. Protection 1 chief executive Timothy Whall will lead the combined company upon the deal’s completion, which is expected by June. “Protection 1’s robust commercial presence will speed ADT’s expansion into the commercial sector,” Mr. Whall said in a statement.

Dealogic looked separately at such add-on acquisitions by financial sponsors. Year to date, such deals were priced at an average premium of 43% to the target’s share price one week before the deal was announced. So ADT might not be getting as great a deal as they first thought at first blush.

That said, ADT faces headwinds. Telecommunications and cable companies have entered its home security market, which could also be hurt by do-it-yourself initiatives. “We believe the company will find it difficult to organically increase ebitda and free cash flow over the next few years,” wrote Keith Schoonmaker, a sector director at Morningstar Inc. in a December report. “ADT’s ability to respond to the competitive environment may be somewhat constrained because of upsized leverage.”

ADT has more than $5 billion in debt, according to S&P Global Market Intelligence, and an enterprise value of close to $10 billion.

ADT’s stock closed at $39.64 on Tuesday, up 47.5%. For the 12 months ended Friday, shares were down 29.5%.

An ADT spokesman declined to comment beyond referring to the company’s announcement of the deal. A spokesman for Apollo Global declined to comment.

UPDATE: This story was updated on February 16 to include an ADT spokesman’s response to a request for comment and an Apollo Global spokesman’s declining to comment. It was also updated to include its 12 month share performance as of Friday as well as Tuesday’s closing share price.

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